To avoid MD altogether, you'd have to get on 250W at Staunton or 33W at Harrisonburg, then Route 48 to Weston, WV, then north on I79 through Morgantown and almost to Pittsburgh before making your way back east.
There's not really any need to take a longer route than you have to, nobody is going to pull you over to check for guns. If you're that worried about it, stop in Potomac Mills or Springfield to fuel up so you don't have to stop until PA, and don't do anything to get pulled over. The only real reason to avoid 95N in MD and DC is the traffic.